[issue25377] Mention octal format of mode argument of os.chmod
New submission from Karl Richter:
`help(os.chmod)` doesn't explain that it expects an octal number for its `mode` argument. This is very confusing for beginners and people who are not involved with filesystems and permissions every day. It doesn't need to be explained, just mentioned, maybe with a link to an extended explanation.
Example for confusion: http://stackoverflow.com/questions/15607903/python-module-os-chmodfile-664-d...
----------
assignee: docs@python
components: Documentation
messages: 252817
nosy: docs@python, krichter
priority: normal
severity: normal
status: open
title: Mention octal format of mode argument of os.chmod
type: enhancement
versions: Python 2.7
_______________________________________
Python tracker
R. David Murray added the comment:
The main docs do not mention octal, but instead point to the constants in the stat module. The help text currently says "Operating-system mode bitfield", which is in fact accurate. A decimal number is *not* a bitfield (although it can be interpreted as one, giving the unexpected results).
However, the help doc could be enhanced to say "Operating-system mode bitfield, see stat module for symbolic constants.".
Basically, the fact that octal works is an historical accident due to it working that way on unix, but ideally should not be relied upon by python code (though of course it will be :).
----------
nosy: +r.david.murray
_______________________________________
Python tracker
Georg Brandl added the comment:
A short sentence like
Be careful when using number literals for *mode*. The conventional UNIX notation for numeric modes uses an octal base, which needs to be indicated with a ``0o`` prefix in Python.
should be a good addition here. (I wonder why it isn't there, I seem to recall an earlier issue about this.)
----------
nosy: +georg.brandl
_______________________________________
Python tracker
Change by Serhiy Storchaka
Change by Ama Aje My Fren
Ama Aje My Fren
participants (5)
-
Ama Aje My Fren -
Georg Brandl
-
Karl Richter
-
R. David Murray
-
Serhiy Storchaka